Frequently Asked Questions on Certificate Process, NOM Marks

It is a technical regulation (of mandatory compliance) issued by competent agencies through their respective National Standards Committee, according to what is stated in Federal Law on Metrology and Standardization (LFMN - Ley Federal Sobre Metrología y Normalización), Article 40.

NOMs enforce minimum safety requirements that must be complied with by products, processes, facilities, systems, activities, services, or production/operation methods, as well as terminology, symbology, packaging, marks, and/or consumer information.

A standard created by a National Standards Organization or, in its absence, governmental branches, according to the Federal Law on Metrology and Standardization (LFMN - Ley Federal Sobre metrología y Normalización), Article 54. An NMX provides common and recurring rules, specifications, attributes, test methods, guidelines, features, or directives applied to products, processes, facilities, systems, activities, services, or production/operation methods, as well as terminology, symbology, packaging, marks, and/or consumer information.

It is intended to help improve processes, products or services according to the specific requirements of manufacturers and consumers who have special needs. These are not mandatory and establish minimum safety and operation requirements for products, processes, and services.

Mandatory compliance only applies to the following cases:

• When the interested party states, by means of certification marks, that their products, processes, or services comply with the respective requirements.
• When a NOM Standard demands the enforcement of and compliance with an NMX in particular.
• When products, goods, or services that have been acquired, rented, or hired by federal public administration agencies or organizations must comply with the corresponding standard.

Basically, a NOM is a mandatory compliance standard (technical regulation) and an NMX is a voluntary compliance standard. However, a NOM may demand that an NMX be complied with if such NOM states that a product must be evaluated by the scope of an NMX in particular. Another important difference is that NOMs only apply to product minimum safety requirements, while NMXs include operation requirements as well.

Upon being issued by a governmental branch, NOM standards may be obtained, free of charge, according to the Official Mexican Standards catalog published by the Secretary of Economy or on the website of the corresponding issuing organization.

In general, NMXs are NOT free of charge and you must submit a request to the issuing Standardization Organization. However, a Mexican Standards catalog published by the Secretary of Economy lists the titles of each NMX standard.

Having a certificate of compliance with NOM is mandatory for some products at the moment they are imported into Mexico. This is established by the tariff code applied to the product (please refer to question #9.)

Yes. As a third-party Product Certification Organization, UL issues NOM and/or NMX certificates according to the standards and certification schemes for which we are credited. (Please visit the PCO Services section)

Mexican Laws state that only companies located in Mexican territory, or in a country with which Mexico has signed a Free Trade Agreement or Treaty that specifies surveillance activities, can obtain a NOM certificate. (Please refer to question #12.)

Yes. The Mexican legal frame states that manufacturers who own a certificate may grant its ownership extension to one or more distributors, traders, or importers, as long as the certificate has been issued under Scheme I. (For more information, please visit the Certification Schemes section.)

In order to obtain such ownership, both parties must submit the corresponding documentation to UL de México.

It is important that foreign manufacturers (certificate owners*) keep in mind that, upon entering the country, the importer will be requested to show the corresponding personalized certificate. In other words, the certificate to be presented must include the name of the importing company.

* Please refer to questions #6 and #12.

The Product Certification Process is governed and established by the Federal Law on Metrology and Standardization (LFMN - Ley Federal sobre Metrología y Normalización) and related Regulations, Conformity Assessment Policies and Procedures, including general certification criteria approved by the General Directorate for Standards, as well as applicable international agreements and guidelines. (Go to Legal Frame.)

Harmonized Tariff Codes are used as a determining parameter to identify applicable technical regulations (NOMs) required when a product enters the country, according to the "Secretary of Economy Agreement to Issue General Rules and Criteria on Foreign Trade (NOMs Agreement,)" published in the Official Gazette on July 6, 2007.

Even though Mexican standards are based on international standards, international compliance certificates are only valid through a Mutual Recognition Agreement between Accredited Certification Organizations. At the moment, certificates issued by other international organizations are not valid in Mexico.

However, if you have reports or test results issued by an international laboratory, you may visit the Secretary of Economy website and check whether these documents can be validated through a Mutual Recognition Agreement between Laboratories or between Certification Organizations and Laboratories. This is not part of the product certification process and is only possible if normative document requirements are identical or equivalent/modified and the respective tests are performed to fulfill national requirements. According to Federal Law on Metrology and Standardization (LFMN - Ley Federal sobre Metrología y Normalización,) regulations and guideline ISO/IEC 21-1:2005, "identical" means that the standard (NOM or NMX) has technical contents, structures, and texts that are identical to regional or international standards, or the respective translations present only minimum editorial changes. "Equivalent" and "modified" are understood when part of the Standard contents (NOM or NMX) are identical to the regional or international standard, but contents present national adaptations, more or less requirements, or alternate requirements.

Such agreements must be approved by competent agencies, which list is available at the Secretary of Economy website, under the Agreements section.

No. UL does not determine or suggest a tariff code attributed to a product. According to the Mexican Customs Law (Article 54, first paragraph), Customs Agents are responsible for classifying merchandise at customs check point.

Yes. If the requesting company is located in a country with which Mexico has signed a Free Trade Agreement or Trade and the legal representative is legally domiciled in one of these countries. Additionally, said agreement or treaty must comprehend surveillance activities.

Among the countries with a commercial treaty or agreement that comprehends surveillance are: United States, Canada, Chile, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, Colombia, Bolivia, Iceland, Liechtenstein, Norway, Switzerland, European Union, Israel, Japan, Brazil, and Paraguay. However, upon the client's request, at any moment we may verify whether other countries were added to (or suspended/removed from) the list.

If the requesting company is located in a country with which Mexico has not signed a Free Trade Agreement or Treaty, the company must have a legal representative based in Mexico.

It is a group of products that share the same type and category (new, rebuilt, used, etc.) and, despite different aesthetical features or appearance, they have the same design characteristics that assure compliance with the corresponding NOM, according to criteria stated by the Conformity Assessment Policies and Procedures (Políticas y Procedimientos para la Evaluación de la Conformidad) and/or "Approved General Criterion for Certification Activities" (Criterios generales en materia de certificación aprobados por la dependencia competente.) (Note: These criteria are not available on the Internet. You may request a copy from the issuing organization or the Secretary of Economy directly through the General Directorate for Standards.) You may download the "Family Grouping Criteria" that applies to the product being certified (identified by standard) in the Required Documents section found at the PCO Services page.

The representative model will be selected according to the following:

1. Established family grouping criteria.
2. Models that present more variations and/or electric components, as well as types of material, as applicable.
3. Number of allowed models per family product group.

UL personnel will address your concerns regarding how to group products into a family and/or select those that predominantly represent the category, which must be submitted to laboratory testing. Otherwise, if you prefer, you must request that we create a family grouping as an additional service. In such case, you must submit a free-form request and the required technical information so that we can analyze the product.

Test result reports will only be accepted when issued by laboratories subcontracted by UL, which must be certified by the Mexican Accreditation Entity, A.C. (

- Entidad Mexicana de Acreditación) and approved by the competent agency, as stated in Federal Law on Measurement and Standardization (LFMN - Ley Federal sobre Metrología y Normalización.) Please check the List of Subcontracted Laboratories.

Please keep in mind that if a product has been or will be evaluated by a laboratory in a foreign territory, this laboratory must have a Mutual Recognition Agreement with a peer certified and approved in Mexico that performs the corresponding nationally focused tests. (Please refer to question #10.)

A list of laboratories that have signed such agreements can be found on the Secretary of Economy website, under the Agreements section.

There you will find the agreements that were specifically signed by UL Inc. in 2000 and extended in 2003. For the latest updates from 2006 and 2007, please contact us directly.

NOM marks can only be used when a product compiles with an Official Mexican Standard. Additionally, product labels or marks (and their accessories) must comply with product marking requirements stated in the applicable product standards and the NOM-008-SCFI-1993, "General System of Measurement Units."

It is crucial that data presenting decimal values use a comma, not a dot (for example: 25,5 V instead of 25.5 V.) Additionally, we must mention that electric and electronic products must comply with consumer information standards NOM-024-SCFI-1998, "Commercial Information for Packaging, Instruction Guides, and Warranties for Electronic, Electrical and Household Appliances," as long as the applicable product safety standard does not regulate the corresponding consumer information. Otherwise, the corresponding product standard item must be complied with if it regulated such product.

On the other hand, product certification marks must correspond to UL marks approved and evaluated during the certification process, according to the Mark Usage Manual provided when the certificate is first issued. If changes are made to the mark, UL must be notified in writing.

In all cases, two copies of the "Certification Services Application" and the original copy of the general and/or specific technical documentation must be submitted, depending on the scheme under which your product will be certified. A list of general and specific technical documentation can be found at the "Required Documentation" section of our PCO Services page, as well as on the back of our Application Form.

On the other hand, if this is a first-time application, you must additionally submit the legal documents requested on such application (or PCO Services page.) Both the Application Form and the Service Agreement are available for download in our PCO Services page, in the "Required Documentation" section, or at our offices.

The application will only be accepted if the required documents are properly filled out and attached to it, along with the Deposit Slip for Certification Services, according to our current Price List. Response time for compliance evaluation processes will be of seven (7) business days for new products or twenty (20) business days (at most) for the remaining categories, from the following business day after the application is received and, if applicable, after the detected flaws have been corrected.

The original application, as well as attached documents, and document check list will be assigned a reference number so that the applicant can follow up on certification or dictum process. Copies of the application form and checklist will be sealed in an envelope by UL and returned the to the applicant once the corresponding payment is made.

When renewing a certificate, you must additionally submit the following:

• A freeform written letter requesting the renewal and stating that the products included in the certificate, as well as the information provided for certification purposes have not been changed in any way.
• The original certificate.
• Test report or product compliance notice sampled by UL.

If you request a renewal with changes to the scope, you must submit the applicable additional technical information described in the application form.

If the application form and/or Service Agreement have been altered, they will not be accepted. Application receipt does not guarantee that the corresponding certificate or dictum will be issued, for it depends on resolving the compliance evaluation analysis.

The standard voltage in Mexico is 127 V of alternate current. In case of double or triple phase items, 120/240 V, 220Y/127 V, 480Y/277 V, and 480 V are preferred values.

According to Article 18, Section II of the Electricity Public Services Law, high-, medium-, or low-tension tolerance cannot exceed ten percent (± 10%).